This project is concerned with analyzing the cellular organization of the brain, especially the cerebral cortex, by means of coordinated studies of electron micrographs, Golgi preparations, and experimental degeneration. Representative regions, such as the visual cortex and the cerebellar nuclei, will be selected for detailed study. Emphasis will be placed on interconnections between cells and fibers in an attempt to construct detailed circuit diagrams for these regions that will be useful for physiological investigation. Nerve fibers, cells and their processes will be characterized and classified according to their shapes, junctions, and cytological features and synapses will be identified as to their sources. This information is necessary in order to understand how neural function results in coherent behavior. BIBLIOGRAPHIC REFERENCES: Palay, S. L. Preface to an English translation of Ramon y Cajal: A new concept of the histology of the central nervous system (1892). In: Neurologic Classics in Modern Translation by D. A. Rottenberg and F. H. Hochberg. Hafner/Macmillan, New York, 1976. Peters, A., S. L. Palay, and H. de F. Webster. The Fine Structure of the Nervous System: The Neurons and Supporting Cells. Saunders, Philadelphia, 1976.